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1. Field of the Invention
The present invention relates generally to bone implants and, more particularly, to biocompatible forms for use in supporting bone graft material.
2. Description of the Art
When a person experiences a loss of teeth due to trauma or other circumstances, or has teeth with periodontal disease, there is often a loss of interproximal crestal alveolar bone. This bone loss may also result in the loss of a person""s interproximal or papillary oral tissue between the corresponding teeth and may cause a bone defect that is very unappealing aesthetically, and difficult to restore. The greater the atrophy of this alveolar bone, in either the maxilla or mandible, the less predictable the regeneration of this bone will be using current grafting procedures and associated structures, including those which are either permanently or temporarily implanted. Without the proper regeneration of this bone defect, any replacement tooth is likely to be mal-positioned, out of proportion and shape and form and lack interproximal tissue for a natural appearance.
The loss of teeth or periodontal disease may also result in the loss of root prominence alveolar bone, in either the maxilla or mandible. In the case of the mandible, the loss of teeth or periodontal disease may also result in a loss of mylohyoid ridge bone on either one or both sides of the mandible. Loss of root prominence alveolar bone or mylohyoid ridge bone further complicates the ability of the dentist to properly regenerate the lost bone and makes it more likely that the artificial tooth will be improperly positioned since the corresponding dental implant or support structure is supported by the root prominence bone and, depending on the particular tooth, may also be supported by the mylohyoid ridge bone.
Many attempts have been made to regenerate normal bone height and contours ranging from block grafts of bone, to grafts supported by screws or other metal supports. Known conventional graft techniques have failed to regenerate bone contours predictably and often result in placing grafted bone in locations where it is not needed, or regenerate bone that is over or under contoured. This often causes the patient to have multiple tissue and bone surgeries to correct the contours of the first graft.
One of the main goals in any attempt to replace a missing tooth is to position the tooth so that it will restore the natural appearances of the surrounding support bone and tissue. However, with the lack of bone in the atrophied maxilla or mandible, these criteria are impossible to accomplish and the results are poor with known techniques and devices. In these cases the dentist is required to restore the missing teeth and tissue contours with an artificial prosthesis, which replaces bone and soft tissue and tooth structure and may be supported by implants. The tissue and the tooth position are corrected by the prosthesis and not by the bone graft. No existing grafting technique attempts to restore the important interproximal scalloped bone contours that are critical to the proper placement of dental implants and aesthetics. One of the main problems associated with conventional methods for replacing teeth with implants is the creation of a xe2x80x9cblack holexe2x80x9d defect between teeth. This results from the lack of bone and tissue between the restored teeth and is very unnatural and is not aesthetically appealing to the patient.
Additional problems exist with known techniques associated with dental implants and bone grafts. For instance, dental implants are often placed in available bone or grafted bone that may not be in the proper position where teeth should be placed. The proper placement may actually be outside the dimensions of the bone. In these cases, if implants are placed in this bone, the dentist is forced to use advanced prosthetic techniques, such as angled abutments, longer transcutaneous abutments and/or custom cast abutments and frameworks to place a crown on an implant in an unnatural position. Usually, the defect is so great that the only prosthesis that can be used is the implant-supported denture, which artificially restores bone, tissue and tooth structure for the patient.
In view of the foregoing deficiencies associated with known devices and methods for regenerating dental bone in order to replace missing teeth, there remains a need for a biocompatible form and associated method for use in supporting bone graft material so that missing alveolar bone is restored to its natural contours thereby permitting dental implants to be placed in the exact position where the missing teeth were originally positioned in the skeletal bone, and allowing missing teeth to be replaced in their natural position.
In view of the foregoing needs, the present invention is directed to a biocompatible form, which may be permanently implanted in a patient""s oral cavity for use in supporting bone graft material, and a method of fabricating the biocompatible form. The biocompatible form may be advantageously utilized in either intraosseous or subperiosteal applications and the configuration of the various embodiments of the biocompatible form permit the regeneration of the scalloped alveolar bone to normal skeletal contours, for either the maxilla or mandible, thereby permitting the restoration of missing teeth in their correct position. More particularly, the biocompatible form of the present invention permits the regeneration of normal interproxlmal bone and tissue for an aesthetic appearance, thereby avoiding the xe2x80x9cblack holexe2x80x9d problems associated with conventional bone grafting techniques. Additionally, the biocompatible form permits the regeneration of root prominence root bone contours and mylohyoid ridge bone contours which contribute to the proper placement of the replacement teeth. The various configurations of the biocompatible form of the present invention permit a dentist to accurately place the bone graft material and add structural support during healing to reproduce the alveolar bone contours required to place the replacement teeth and the associated implants in the correct position.
According to a first aspect of the present invention, a biocompatible form is provided which may be permanently implanted in a patient""s oral cavity for use in supporting bone graft material. The biocompatible form of the present invention is configured such that one or more portions conform to various alveolar bone contours. For instance, at least a portion of the biocompatible form may be configured to conform substantially to a predetermined, human interproximal bone contour, a root prominence bone contour, a palatal contour, a mylohyoid ridge bone contour, a maxillary facial contour, a maxillary lingual contour, a mandibular facial contour or a mandibular lingual contour.
According to a preferred embodiment, the biocompatible form is made of a first side portion, a second side portion and a connecting portion extending between and interconnecting the first and second side portions. The biocompatible form is open opposite the connecting portion and further includes open ends.
The first and second side portions and the connecting portion combine to define an interior channel, with the interior channel being sized and configured to receive at least a portion of an edentulous ridge of the patient and at least a portion of the bone graft material therewithin. The connecting portion of the biocompatible form includes at least one protruding portion, with each of the protruding portions being configured to conform substantially to a predetermined, human interproximal bone contour. The first side portion, second side portion and connecting portion are made of a biocompatible mesh. In one embodiment, the biocompatible form is a metal mesh, which may be fabricated from titanium or a titanium alloy and, in another embodiment, the biocompatible form is a fiber mesh, which may be fabricated from collagen.
In another embodiment, the biocompatible form can be configured to receive at least one dental prosthesis therethrough, with the biocompatible form further made of at least one aperture formed in the connecting portion of the biocompatible form and with each aperture sized to receive one of the dental prostheses therethrough. Each aperture is positioned intermediate an adjacent pair of the protruding portions.
In another embodiment, the first side portion of the biocompatible form may include at least one outwardly protruding portion, with each of these portions being configured to conform substantially to a predetermined human root prominence bone contour. In this embodiment, the second side portion may include at least one outwardly protruding portion, with each of the outwardly protruding portions being configured to conform substantially to a human root prominence bone contour, and with each of the outwardly protruding portions of the second side portion being aligned with one of the outwardly protruding portions of the first side portion.
In those embodiments where the first and second side portions of the biocompatible form include at least one outwardly protruding portion conforming substantially to predetermined human root prominence bone contours, each of the apertures is aligned with an aligned pair of the protruding portions of the first and second side portions, which permits each dental prosthesis to be implanted in an area of regenerated root prominence bone.
In yet another embodiment, having an application for regenerating the alveolar bone of a patient""s mandible, the channel is sized and configure to receive a portion of a predetermined mandibular edentulous ridge. The second side portion may include at least one outwardly protruding each outwardly protruding of these portions being configured to conform substantially to a predetermined, human mylohyoid ridge bone contour.
In yet another embodiment, where the edentulous ridge of the patient is a maxillary ridge, the biocompatible form may further include a palatal portion integral with and extending away from the second side portion. The palatal portion being configured to conform substantially to a predetermined, human palatal bone contour.
The biocompatible mesh includes a first surface facing toward the interior channel of the biocompatible form and a second surface facing away from the interior channel. In those embodiments where the metal mesh is fabricated from either titanium or a titanium alloy, the first surface of the mesh may be sand-blasted and subsequently acid-etched to enhance adherence of the bone graph material to the biocompatible form. This applies to bone implants having either intraosseous or subperiosteal applications. Additionally, in intraosseous applications, the second surface of the mesh screen may also be sand-blasted and subsequently acid-etched to enhance the adherence of the bone graft material to the bone implant. With regard to subperiosteal applications, the second surface of the mesh may be polished to enhance adherence of the patient""s oral mucosal tissue to the biocompatible form. Additionally, in these embodiments, the second surface of the mesh may be treated with titanium nitrate after the surface is polished for aesthetic purposes.
According to a second aspect of the present invention, a method is provided for fabricating a bone implant which may be permanently implanted in a patient""s oral cavity for use in supporting bone graft material. According to one preferred embodiment, the method comprises the steps of acquiring a biocompatible mesh, creating a solid cast mold of an edentulous mandibular or maxillary ridge of a human cadaver skull which includes normal alveolar bone contours, and forming the biocompatible mesh to substantially conform to the contours of the solid cast mold including the contours of the mold corresponding to the normal alveolar bone contours of the human cadaver skull.
The step of forming may involve the step of press fitting the biocompatible mesh to the solid cast mold. The step of acquiring may include the step of selecting the biocompatible mesh from one of titanium, a titanium alloy and a fiber material.
The method of the present invention may be used to fabricate a biocompatible form having application as either an intraosseous implant or a subperiosteal implant. With either application, when the biocompatible mesh is made of either titanium or a titanium alloy, the method of the present invention may further include the steps of sandblasting a first surface of the biocompatible mesh which faces an interior channel defined by the mesh, and subsequently acid-etching the first surface of the mesh after the step of sandblasting, to enhance the adherence of the bone graft material to the biocompatible form. For biocompatible forms having intraosseous application, the method of the present invention may further include the steps of sandblasting a second surface of the biocompatible mesh which faces away from the interior channel, and acid-etching the second surface of the mesh after the step of sandblasting, also for the purpose of enhancing the adherence of the bone graft material to the biocompatible form.
In the instances where the biocompatible form is to be used for subperiosteal applications, the method of the present invention may further include the step of polishing the second surface of the biocompatible mesh to enhance adherence of the patient""s oral mucosal tissue to the implant. In this embodiment, the method of the present invention may further include the step of treating the second surface of the biocompatible mesh with titanium nitrate, for aesthetic purposes.
According to another aspect of the invention, the biocompatible form can be customized to further conform to at least a portion of the alveolar bone contours of the patient""s edentulous ridge. This method includes the steps of taking a CAT Scan of at least one of a patient""s maxillary or mandibular ridge, which comprises an edentulous ridge, and fabricating a resin mold of the patient""s edentulous ridge from an output of the CAT Scan.
The method of the present invention may also further involve the steps of taking an impression of a dental arch of the patient which is disposed in opposing relationship with the edentulous ridge of the patient and making a dental stone mold of the patient""s dental arch. In this embodiment, the method further involves the steps of mounting the resin mold of the patient""s edentulous ridge and the dental stone mold of the patient""s opposing dental arch on a dental articulator, with the resin mold including an area corresponding to one or more missing teeth, and occluding a coronal portion of at least one tooth to the dental mold in a position opposite the area of missing teeth on the resin mold.
The method may further include the steps of positioning the formed biocompatible mesh on the resin mold over the area corresponding to one or more missing teeth and closing the dental articulator such that the dental stone mold is disposed in close proximity to the resin mold and the mesh screen.
According to another aspect of this invention, an intraosseous dental implant which is permanently implanted in a patient""s oral cavity is provided. This dental implant is made of a membrane barrier layer, a bone graft material and a biocompatible form. This implant involves the membrane barrier layer substantially covering the bone graft material, the membrane barrier layer contacting a patient""s oral mucosal tissue; the bone graft material substantially covering a biocompatible form, the biocompatible form having a first side portion, a second side portion and a connecting portion extending between and interconnecting the first and second side portions, the biocompatible form being open opposite the connecting portion and further including open ends, the first and second side portions and the connecting portion combining to define an interior channel, the interior channel being sized and configured to receive at least a portion of an edentulous ridge of the patient and at least a portion of the bone graft material therewithin; and the connecting portion including at least one protruding portion being configured to conform substantially to a predetermined, human interproximal bone contour; and at least a portion of the bone graft material disposed therewith the biocompatible form.
According to another aspect of this invention, a subperiosteal dental implant which is permanently implanted in a patient""s oral cavity is provided. This dental implant is made of a membrane barrier layer, bone graft material and a biocompatible form. This implant involves the membrane barrier layer substantially covering the biocompatible form, the membrane barrier layer contacting a patient""s oral mucosal tissue; the biocompatible form comprising a first side portion, a second side portion and a connecting portion extending between and interconnecting the first and second side portions, the biocompatible form being open opposite the connecting portion and further including open ends, the first and second side portions and the connecting portion combining to define an interior channel, the interior channel being sized and configured to receive at least a portion of an edentulous ridge of the patient and at least a portion of the bone graft material therewithin, the connecting portion including at least one protruding portion being configured to conform substantially to a predetermined, human interproximal bone contour, and at least a portion of the bone graft material disposed therewith the biocompatible form.
According to another aspect of this invention, an intraosseous dental implant which is permanently implanted in a patient""s oral cavity is provided. This dental implant is made of a membrane barrier layer, bone graft material and a biocompatible form. This implant involves the membrane barrier layer substantially covering the bone graft material, the membrane barrier layer contacting a patient""s oral mucosal tissue; the bone graft material substantially covering a biocompatible form comprising a first side portion, a second side portion and a connecting portion extending between and interconnecting the first and second side portions, the biocompatible form being open opposite the connecting portion and further including open ends, the first and second side portions and the connecting portion combining to define an interior channel, the channel being sized and configured to receive at least a portion of an edentulous ridge of the patient and at least a portion of the bone graft material therewithin; the first side portion including at least one outwardly protruding portion, each the outwardly protruding portion being configured to conform substantially to a predetermined, human root prominence bone contour; the second side portion includes at least one outwardly protruding portion, each the outwardly protruding portion being configured to conform substantially to a predetermined, human root prominence bone contour; and the first side portion, the second side portion and the connecting portion being made of a biocompatible mesh; and at least a portion of bone graft material disposed therewith the biocompatible form.
According to another aspect of this invention, a subperiostial dental implant which is permanently implanted in a patient""s oral cavity is provided. This dental implant is made of a membrane barrier layer, bone graft material and a biocompatible form. This implant involves the membrane barrier layer substantially covering a biocompatible form, the membrane barrier layer contacting a patient""s oral mucosal tissue, the biocompatible form comprising a first side portion, a second side portion and a connecting portion extending between and interconnecting the first and second side portions, the biocompatible form being open opposite the connecting portion and further including open ends, the first and second side portions and the connecting portion combining to define an interior channel, the channel being sized and configured to receive at least a portion of an edentulous ridge of the patient and at least a portion of the bone graft material therewithin; the first side portion including at least one outwardly protruding portion, each the outwardly protruding portion being configured to conform substantially to a predetermined, human root prominence bone contour; the second side portion includes at least one outwardly protruding portion, each the outwardly protruding portion being configured to conform substantially to a predetermined, human root prominence bone contour; and the first side portion, the second side portion and the connecting portion being made of a biocompatible mesh; and at least a portion of bone graft material being disposed therewithin the biocompatible form.
Another aspect of this invention provides a surgical kit including a sterilizable container adapted to contain articles. This kit can include a biocompatible form which may be permanently implanted in a patient""s oral cavity for use in supporting bone graft material; the biocompatible form includes a first side portion, a second side portion and a connecting portion extending between and interconnecting the first and second side portions, the biocompatible form being open opposite the connecting portion and further including open ends, the first and second side portions and the connecting portion combining to define an interior channel, the interior channel being sized and configured to receive at least a portion of an edentulous ridge of the patient and at least a portion of the bone graft material therewithin; the connecting portion including at least one protruding portion, each of the protruding portion being configured to conform substantially to a predetermined, human interproximal bone contour or portions thereof. The kit further includes a plurality of devices adapted to attach the biocompatible form to a patient""s edentulous ridge and dental tools, such as a pair of molding pliers and a pair of scissors.